MySQL 5.5 Release Notes

Abstract

This document contains release notes for the changes in each
release of MySQL 5.5, up through MySQL
5.5.44. For information about changes in a different
MySQL series, see the release notes for that series.

Updates to these notes occur as new product features are added, so
that everybody can follow the development process. If a recent
version is listed here that you cannot find on the download page
(http://dev.mysql.com/downloads/), it means that the version has
not yet been released.

The date mentioned with a release version is the date of the last
revision control system changeset on which the release was based,
not necessarily the date when the distribution packages were made
available. The binaries are usually made available a few days after
the date of the tagged changeset because building and testing all
packages takes some time.

The documentation included in source and binary distributions may
not be fully up to date with respect to release note entries because
integration of the documentation occurs at release build time. For
the most up-to-date release notes, please refer to the online
documentation instead.

Previously, MySQL development proceeded by including a large set
of features and moving them over many versions within a release
series through several stages of maturity (Alpha, Beta, and so
forth). This development model had a disadvantage in that
problems with only part of the code could hinder timely release
of the whole.

MySQL development now uses a milestone model. The move to this
model provides for more frequent milestone releases, with each
milestone proceeding through a small number of releases having a
focus on a specific subset of thoroughly tested features.
Following the releases for one milestone, development proceeds
with the next milestone; that is, another small number of
releases that focuses on the next small set of features, also
thoroughly tested.

MySQL 5.5.0-m2 is the first release for Milestone 2. The new
features of this milestone may be considered to be initially of
beta quality. For subsequent Milestone 2 releases, we plan to
use increasing version numbers (5.5.1 and higher) while
continuing to employ the “-m2” suffix. For
Milestone 3, we plan to change the suffix to “-m3”.
Version designators with “-alpha” or
“-beta” suffixes are no used.

You may notice that the MySQL 5.5.0 release is designated as
Milestone 2 rather than Milestone 1. This is because MySQL 5.4
was actually designated as Milestone 1, although we had not yet
begun referring to milestone numbers as part of version numbers
at the time.